For stuff being scrubbed off the web, I sincerely doubt that her parents know at this point. To say the least, that would be a very, very awkward conversation for her to have, would likely involve them seeing this thread specifically, and I don't suspect that Isabella has told her parents yet or wants them to know.
If that happened, they'd see her trash talking her sister's issues with infidelity, the porn that she's into, her love of pedophilia, long term involvement in manipulation of an autistic individual, etc.
I'm just presuming that other sites taking down content related to this is a preliminary move by them, more because of the potential to be sued for libel and not wanting to deal with any potential future legal cases if it is, indeed, libel or not, rather than anything else.